Step frame



FIG. 1 is a front perspective view of the step frame of the present invention;

FIG. 2 is a rear view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a left-side view thereof;

FIG. 5 is a right-side view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The dot-dashed broken lines shown in the figures are for the purpose of illustrating boundaries of the claimed design and form no part of the claimed design. 

CLAIM The ornamental design for a step frame, as shown and described. 